This relates to semiconductor processing and, particularly, to techniques for filling cavities.
A high aspect ratio cavity is a cavity, hole, depression, or trench whose depth is twice its width or more. Because of the high aspect ratio, cavity filling tends to be problematic. For example, in the course of filling such cavities, seam formation may result. A seam is basically an opening or crack within the filled material. The seam is then prone to subsequent etching in ensuing processing. Another possibility is the formation of overhangs near the top of the trench which close off the trench and prevent complete filling of the trench.